I've used Advanced Circuits (4pcb.com) in the past, and have had little problem with them. I just got back some boards I recently ordered via their $33 each program. Images below. The dark marks between the traces of 3 of 4 of the boards are shorts.
I am sure they will make good on this -- I already talked to them. This is just an illustration that even vendors with a history of good quality can make mistakes.
I am sure they will make good on this -- I already talked to them. This is just an illustration that even vendors with a history of good quality can make mistakes.